GE D60 Instruction Manual

Also see for D60: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

5-314 D60 Line Distance Protection System GE Multilin5.7 CONTROL ELEMENTS 5 SETTINGS5Generally, this scheme uses an overreaching zone 2 distance element to essentially compare the direction to a fault at allterminals of the line. Ground directional overcurrent functions available in the D60 can be used in conjunction with the zone2 distance element to key the scheme and initiate operation. This increases the coverage for high-resistance faults.The scheme is intended for three-terminal and two-terminal applications with weak-infeed conditions. As a long reach of theoverreaching distance element may be required for three-terminal applications, transient blocking logic is provided for bothdistance and ground directional overcurrent elements. In order to cope with weak-infeed conditions an echo feature ismade available.By default the scheme uses the reverse-looking zone 4 distance element to identify reverse faults. Additionally, reverse-looking ground directional overcurrent functions can be used in conjunction with the zone 4.For proper operation, the zone 2 and 4 phase and ground distance elements must be enabled, configured and set per rulesof distance relaying. The line pickup element should be enabled, configured and set properly to detect line-end-open/weak-infeed and undervoltage conditions. If used by the scheme, the selected ground directional overcurrent function(s) must beenabled, configured, and set accordingly.In single-pole tripping applications, the scheme uses local fault type identification provided by the phase selector togetherwith information received from the remote terminal. The scheme generates output operands ( HYBRID POTT TX1 throughHYBRID POTT TX4) that are used to transmit the signal to the remote terminal(s). Choices of communications channelinclude remote inputs/outputs and telecommunications interfaces. When used with telecommunications facilities the outputoperand should be assigned to operate an output contact connected to key the transmitter at the interface. When used withtelecommunications facilities the output operands should be assigned to operate output contacts connected to assert theindividual bits at the interface.To make the scheme fully operational as a stand-alone feature, the scheme output operands must be configured to inter-face with other relay functions, output contacts in particular. Typically, the output operands should be programmed to initiatea trip, breaker fail, and autoreclose, and drive a user-programmable LED as per user application.When used in conjunction with the trip output element, the scheme is pre-configured to initiate trip, breaker fail and single-pole autoreclose actions.• HYB POTT BLOCK: This setting allows the user to assign any FlexLogic operand to block the scheme. Contact inputsfrom a pilot cut-out switch are typically used for this purpose.• HYB POTT PERMISSIVE ECHO: If set to “Enabled”, the scheme sends a permissive echo signal to the remote end(s)using a pre-programmed logic (refer to the logic diagram below). If set to “Custom”, the echo signal is sent if a condi-tion selected via the HYB POTT ECHO COND setting is satisfied. The echo is sent only once and then the logic locks outfor the time specified by the ECHO LOCKOUT setting. The duration of the echo pulse is settable as ECHO DURATION.Operation of the overreaching protection elements (distance zone 2 or GND DIR O/C FWD setting) inhibits the echo.• HYB POTT ECHO COND: This setting specifies a user-selected echo condition and applies only if the HYB POTT PER-MISSIVE ECHO is set to “Custom”.• HYB POTT WEAK INFEED: If this setting is set to “Enabled”, the scheme activates both the keying and operatingpaths using a pre-programmed weak infeed logic (refer to the logic diagram below). If this setting is set to “Custom”,the weak infeed condition is to be specified by the user via the HYB POTT W/I COND setting.• HYB POTT W/I COND: This setting specifies user-selected weak infeed condition and applies only if the HYB POTTWEAK INFEED is set to “Custom”.• HYB POTT RX PICKUP DELAY: This setting enables the relay to cope with spurious received signals. The delayshould be set longer than the longest spurious TX signal that can be received simultaneously with the zone 2 pickup.The selected delay will increase the response time of the scheme.• TRANS BLOCK PICKUP DELAY: This setting defines a transient blocking mechanism embedded in the hybrid POTTscheme for coping with the exposure of both the over-reaching zone 2 and ground directional overcurrent function tocurrent reversal conditions.The transient blocking logic applies to both operate (trip) and send (transmit) paths. Identifying the fault as a reversefault prevents the scheme from both operating and keying the channel. If the reverse fault condition prevails for TRANSBLOCK PICKUP DELAY, the blocking operation will be extended by the transient blocking timer for TRANS BLOCK RESETDELAY. This allows riding through current reversal conditions.However, if distance zone 1 picks up during the transient blocking condition, the blocking action is removed. This is tocope with evolving faults when an external fault is followed by an internal fault. Without the zone 1 feedback, the tripwould be delayed unnecessarily.